MSWindows sandboxing problems with paths

Hi. I’ve been seeing about converting a Xojo app for windows store. I’ve followed this instructions.
I have a problem and a doubt.
Once I’ve converted my app (installer made with InnoSetup -I need to add zlib.dll to System32-) with DesktopAppConverter and obtained an appx (with certificates and so on) everything go well except paths. I need to store app data (sqlitedb, files…), I use specialfolder.applicationdata which points to \Users\Username\AppData\Roaming\Appname BUT when the sandboxed appx is installed, the “applicationdata” itself now is in \Users\Username\Local\Packages\AppName_xxxxxxxxxxxxx\LocalCache\Roaming\AppName.
Accesing to DB, creating reports, adding files… and store them in this location runs with no problem. but when i try to access to this files (with folderitem.launch -folderitem points to specialfolder.applicationdata.child(blah).child(blah)) i get and error because MSWindows is trying to show the file located in \Users\Username\AppData\Roaming\Appname\Folder\file.pdf -for example- which doesn’t exist; the real file is located (\Users\Username\Local\Packages\AppName_xxxxxxxxxxxxx\LocalCache\Roaming\AppName\Folder\file.pdf). I don’t know why, sandboxed appx are able to find correctly its sandboxed “specialfolder.applicationdata” for saving, storing… files or for DB CRUD, BUT is NOT able to “update” the path for recovering data (showing .pdf files mainly).
The app is a Gradebook made with xojo2017.r3. The installer and Folder with sandboxed app is here
When a new version is released the innosetup installer keeps the ApplicationData if exits. Anybody knows if this behaviour is the same with a sandboxed appx (obviously the applicationData pointing to \Users\Username\Local\Packages\AppName_xxxxxxxxxxxxx\LocalCache\Roaming\AppName)?.